A significant problem in machinery vises is the inability, for one reason or another, to clamp and hold workpieces safely. This is particularly true in those instances where the workpiece is dislodged during operation of the machinery. For example, in the operation of a powered horizontal metal cutting bandsaw, when the workpiece comprises sheet metal, angle iron or the like and the blade being used in machine is too coarse for the application, it is not unusual for a tooth of the blade to get caught in the workpiece. Rather than cutting the workpiece, the blade dislodges it from the vise, often throwing the workpiece through the air for a considerable distance at high velocity. This condition is generally known as "kickback" or "fly-away" of the workpiece and serious injury to the operator or other persons in the vicinity of the machinery may result.
Various attempts in the prior art to provide a vise capable of safely securing a workpiece have not proven adequate to prevent accidental kickback or fly-away of a workpiece during operation For example, U.S. Pat. Nos. 1,125,207; 1,242,182; 1,938,337; 1,951,869; 2,334,911; 2,806,411; 3,785,635; 3,856,292; 4,114,868; 4,261,558; French Patent No. 1,252,495 and Swiss Patent No. 132,378 disclose various configurations for vise or clamping devices, whereby finger-like projections and other movable projections engage a workpiece, typically on the side, so as to produce lateral forces to hold or clamp the workpiece in place. None of these prior art references, however, provide a safety feature to prevent kickback or fly-away of a workpiece.
U.S. Pat. Nos. 3,286,744; 3,734,485; 4,236,430 and 4,340,211 disclose various vise or clamping devices, whereby finger-like projections or other movable projections engage or clamp a workpiece on the top of the workpiece to hold the workpiece in a vise apparatus. However, these prior art references provide complex and expensive means for exerting downward forces to clamp a workpiece downwardly toward the vise bed. None of these references provide means for inhibiting or preventing kickback or fly-away movement of a workpiece in the event that the workpiece becomes dislodged from the vise.
In view of the disadvantages inherent in the prior art, it would be desirable to provide an apparatus for safely inhibiting fly-away movement of a workpiece which is relatively simple and inexpensive to manufacture and operate.